My LG dryer had a 4 prong cord and my new house is a 3 prong outlet. We changed the cord to the 3 prong cord, turned it on and it lit up for 1 second then turned off. We first checked the circuit breaker which was fine. After looking at some forums we realized we were suppose to ground it twice. So the main ground and hot wires are in place, but the smaller 2nd ground wasn't. We now have that one grounded also but it still won't power on. The only thing that comes on is the light inside the dryer. What could be wrong with it?

Well a dryer works off of 240 Volts. It splits that up. The light in your dryer uses 110V but the heating elements use 240V. The motor which won't start uses 110V and the controls use 110V. There could be a couple prolems and of which it could be. You need to get a meter and check that both leads are getting 110V from each hot lead to neutral. Also when you switch back to a three prong, the ground is no longer separate and you need to jumper the ground to the neutral terminal. (When you have a four prong cable the ground is separate for the fact that its safer). Even if the circuit breaker is on, I would check that each terminal of the breaker is putting out 110V to ground (If so it needs to be replaced, its simple to do just wire it like the other one, and turn off main power to replace it so there is no power to the buss bar its attached to. Just be careful not to touch the main feed wires to the panel as they are still powered). If none of this pans out, it could also be that your dryer needs that four wire plug (I would check with your manufacturer). Either way, if your dryer worked before it shouldn't be a dryer problem now